In the literature, printed-circuit boards, referred to as flex-rigid printed-circuit boards, include two rigid end sections provided with electric and/or electronic components such as plated-through holes, printed circuit traces, and active or passive electronic component parts. The two rigid sections are interconnected by an elastically deformable middle section. Such printed-circuit boards can be bent about the middle section, and can consequently be mounted in electric devices in a very space saving manner. In particular, it is possible to connect a rigid end section of the printed-circuit board to an impact-and vibration-sensitive component part which is supported in a device housing in a vibration-damped manner and to connect the other rigid end section to a fixed housing part, for example, a plug part. The elastically deformable middle section prevents impact and vibration loads from being transmitted to the impact- and vibration-sensitive component part. However, it is a disadvantage that the middle section of the known flex-rigid printed-circuit boards, in spite of its elasticity, is still too stiff so that the known flex-rigid printed-circuit boards still partially transmit impact and shaking loads to the sensitive component parts.
The printed-circuit board according to the present invention obviates this disadvantage. This is achieved by at least one opening provided in the elastically deformable middle section of the conductor foil, the region of the middle section surrounding the opening forming at least two bars extending in a direction from the first rigid section to the second rigid section and laterally bordering the at least one opening, the printed circuit traces being arranged on the bars. By the openings in the middle section, the stiffness of the middle section is advantageously reduced and the elasticity is increased. The bars remaining in the middle section can have a very form design so that the stiffness of the conductor foil is significantly reduced at least in the region provided with the bars. In the borderline case, one single bar can be provided for each printed circuit trace, the width of the bar being only slightly greater than the width of the printed circuit trace. By these measures, it is achieved that shaking and vibration loads are not transmitted to the sensitive components parts, for example, sensor elements connected to the one rigid section, at all or only to an extremely small extent. The at least one opening in the middle section can advantageously be made by a simple punching operation. The printed-circuit board can be manufactured in a very inexpensive manner since greater changes to the manufacturing process are not required.
It is advantageous for the at least one opening to have the form of a slit, particularly the form of an oblong hole, extending in a direction from the first rigid section to the second rigid section.
The stiffness of the elastically deformable middle section can still be further reduced by providing a plurality of slit-type openings in the middle section, each opening being laterally bordered by two bars running parallel to each other. The bars can expediently be provided with printed circuit traces on the top side and bottom side.
In the housing of an electric/electronic device, it is particularly beneficial for the first rigid section of the printed-circuit board to be connected to an impact- and vibration-sensitive component part of the device which is supported in the device housing in a vibration-damped manner, and to fasten the second rigid section of the printed-circuit board to a fixed housing part, preferably a plug part mounted on the housing. Then, the distance between the first rigid section and the second rigid section of the printed-circuit board can be adjusted advantageously in that the bars connecting the two rigid sections bend in a loop-type manner. The loops effectively isolate the impact-sensitive component part from the housing part and effectively prevent impacts and vibrations from being transmitted to the sensitive component part, for example, a sensor, via the printed-circuit board.